This invention relates to a carrier tape for receiving therein electronic components, and more particularly to a carrier tape suitable for receiving therein small-sized area types of semiconductor packages such as ball grid array packages (BGA), micro ball grid array packages (.mu.BGA), chip scale packages (CSP), bare chips or the like and a die apparatus for forming the same.
A semiconductor package such as a .mu.BGA or the like includes electrode terminals such as a plurality of electrodes, e.g. solder balls or solder bumps, or the like which are arranged in a matrix-like manner on a bottom surface of a chip mounting substrate or a bottom surface of a chip mold section. Such a semiconductor package, when the electrode terminals of the package are brought into direct contact with a carrier tape while receiving the package in the carrier tape, causes contamination of the electrode terminals, as well as deformation of the electrode terminals due to local application of load to the package. Such contamination of the electrode terminals leads to a failure in soldering of the electrode terminals during mounting of the semiconductor package. Such a failure in soldering is hard to be found because the electrode terminals of the semiconductor package are arranged on the bottom surface of the package which is hard to be observed.
In view of the foregoing, the assignee proposed a carrier tape which is constructed so as to prevent electrode terminals of a semiconductor package such as a .mu.BGA or the like from being brought into direct contact with the carrier tape when the semiconductor package is received in the carrier tape, as disclosed in Japanese Patent Application Laid-Open Publication No. 11930/1996. The proposed carrier tape is formed on a surface thereof with a plurality of receiving depressions or recesses. The receiving recesses are each formed at a periphery thereof with shelf sections, so that a peripheral edge of a bottom surface of each of the semiconductor packages is supported on the shelf sections of the carrier tape while a side of the semiconductor package is abutted against a side surface of one of the receiving recesses to position the semiconductor package on the carrier tape.
In the proposed carrier tape, the shelf sections each include a shelf surface which has a groove formed by an edge of the side surface of a corresponding one of the receiving recesses, to thereby avoid any disadvantage due to a restriction on molding which causes a connection between the shelf surface and the side surface to be formed into an arcuate shape. More particularly, the carrier tape is made by pressure forming, vacuum forming, pressing or the like. Unfortunately, such forming techniques substantially fail to form the shelf surface of the shelf section in a manner to be perpendicularly contiguous to the side surface of the receiving recess due to a restriction on processing or machining accuracy of a forming die, so that the connection between the shelf surface and the side surface is inevitably formed into an arcuate shape. This causes a flat portion on the shelf surface to be decreased in area when the semiconductor package is received in the receiving recess, leading to a disadvantage that each of peripheral edges of the semiconductor package rides on each of the arcuate surfaces, resulting in looseness of the semiconductor package in the receiving recess being produced. Thus, the proposed carrier tape is intended to permit the groove formed on the shelf surface to remove an adverse effect of the arcuate surface, to thereby prevent such looseness of the semiconductor package.
Nevertheless, the carrier tape thus proposed in Japanese Patent Application Laid-Open Publication No. 11930/1996 requires that a strip-like projection for formation of the groove is formed on the forming die by fine processing or machining, so that manufacturing of the forming die is highly difficult and troublesome. Also, the strip-like projection is readily worn due to repeating of the forming, resulting in durability of the forming die being deteriorated.